Propeller milling machine

A propeller milling machine comprising a double-column bridge under which a work is to be placed, a horizontal crossrail laid on the bridge, a plurality of ram assemblies, each assembly containing a corresponding shaft, said plurality of assemblies supported by the crossrail to traverse horizontally thereon and to move vertically at right angles to the rail, a plurality of extension heads each with a built-in extension shaft coupled to the associated ram shaft, a plurality of inclined couplers each of which has at least one inclined face and is turnably interposed between each ram assembly and the associated extension head, and a plurality of angle heads, each angle head swingably connected to a corresponding extension head, each of said angle heads having a built-in main spindle rotatably coupled to the extension shaft at right angles thereto for driving a milling cutter also carried by the angle head and wherein said clamp means includes a piston made fast to the rear end of each angle head, said piston being formed with a diametral groove, an annular row of steel balls movable in the groove toward the axis, a flexible contacting part, a sleeve secured to the extension head while in contact with the contacting part, and a cylinder having an inclined plane for contact with the steel balls, said piston and cylinder wall defining hydraulic fluid chambers in the cylinder.